[x86 setup] edd.c: make sure MBR signatures actually get reported

When filling in the MBR signature array, the setup code failed to advance
boot_params.edd_mbr_sig_buf_entries, which resulted in the valid data
being ignored.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 11 insertions, 13 deletions

diff --git a/arch/i386/boot/edd.c b/arch/i386/boot/edd.c
index d65dd21c09f2..82b5c846a194 100644
--- a/arch/i386/boot/edd.c
+++ b/arch/i386/boot/edd.c
@@ -37,11 +37,10 @@ static int read_mbr(u8 devno, void *buf)
         return -(u8)ax;         /* 0 or -1 */
 }
 
-static u32 read_mbr_sig(u8 devno, struct edd_info *ei)
+static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig)
 {
         int sector_size;
         char *mbrbuf_ptr, *mbrbuf_end;
-        u32 mbrsig;
         u32 buf_base, mbr_base;
         extern char _end[];
 
@@ -57,15 +56,15 @@ static u32 read_mbr_sig(u8 devno, struct edd_info *ei)
 
         /* Make sure we actually have space on the heap... */
         if (!(boot_params.hdr.loadflags & CAN_USE_HEAP))
-                return 0;
+                return -1;
         if (mbrbuf_end > (char *)(size_t)boot_params.hdr.heap_end_ptr)
-                return 0;
+                return -1;
 
         if (read_mbr(devno, mbrbuf_ptr))
-                return 0;
+                return -1;
 
-        mbrsig = *(u32 *)&mbrbuf_ptr[EDD_MBR_SIG_OFFSET];
-        return mbrsig;
+        *mbrsig = *(u32 *)&mbrbuf_ptr[EDD_MBR_SIG_OFFSET];
+        return 0;
 }
 
 static int get_edd_info(u8 devno, struct edd_info *ei)
@@ -132,6 +131,7 @@ void query_edd(void)
         int do_edd = 1;
         int devno;
         struct edd_info ei, *edp;
+        u32 *mbrptr;
 
         if (cmdline_find_option("edd", eddarg, sizeof eddarg) > 0) {
                 if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip"))
@@ -140,7 +140,8 @@ void query_edd(void)
                         do_edd = 0;
         }
 
-        edp = (struct edd_info *)boot_params.eddbuf;
+        edp    = boot_params.eddbuf;
+        mbrptr = boot_params.edd_mbr_sig_buffer;
 
         if (!do_edd)
                 return;
@@ -158,11 +159,8 @@ void query_edd(void)
                         boot_params.eddbuf_entries++;
                 }
 
-                if (do_mbr) {
-                        u32 mbr_sig;
-                        mbr_sig = read_mbr_sig(devno, &ei);
-                        boot_params.edd_mbr_sig_buffer[devno-0x80] = mbr_sig;
-                }
+                if (do_mbr && !read_mbr_sig(devno, &ei, mbrptr++))
+                        boot_params.edd_mbr_sig_buf_entries = devno-0x80+1;
         }
 }